Parasites of skin and muscle

5 Parasites of the Skin and Muscles Flea Infestations What are fleas and how do they thrive? Fleas are obligate blood-sucking insects, which have evolved to live in close proximity to their hosts and the host habitat. In the case of cat fleas and to some extent dog fleas, this adaptation causes severe domestic household infestations. Adult fleas seen on pets are glossy brown/black in colour, flat- tened from side to side, and are equipped with very powerful back legs for jumping. They have a set of combs at the junction of the head and thorax (pronotal ctenidia) and another set near the mouthparts (genal ctenidia). This morphology varies in different species (rabbit fleas, rodent and bird fleas, for example, which may occasionally be found on cats and dogs) and flea species identification can be important in control programmes advised for flea-infested households. Cat and dog fleas may cause intense itching and induce allergic reactions in susceptible animals and they also bite pet owners. Flea infestations are probably the most common ectoparasites of dogs and cats. Although more than 2200 species and subspecies of fleas are known throughout the world, the cat flea Ctenocephalides felis (Fig. 5.1a) remains the dominant species on domestic pets. That said, rabbit fleas, while not per- sistently residing on the pet, are seen regularly in practice, as are infestations of household bird fleas. These incidents are possibly more common now than dog flea infestations, which have become quite rare. Understanding their unique life cycle (and explaining this to clients) is very important before initiating control. Cat and dog fleas produce lots of eggs while on the pet and as these are shaken off they may be widely distributed in the household environment. There they develop into larvae, which feed on dried dirt originating from adult fleas (excess regurgitated blood) and other 64 © CAB International 2018. Parasites and Pets (Elsheikha, Wright & McGarry)

Parasites of the Skin and Muscles detritus. In the infested domestic setting, the accumulated larval offspring de- velop over time into new adults and thereby continuously infest and reinfest pets. Furthermore, the final ‘chrysalis’ stage or pupa (Fig. 5.1b) is sticky and becomes surrounded by debris; in this way it is protected and is resistant to treatments applied to carpets and bedding. Once the pupa has fully devel- oped, the immature or ‘pharate’ adult flea within the cocoon can be stimu- lated to emerge from the cocoon by vibrations, carbon dioxide and heat. Can fleas survive for long periods? The entire life cycle of C. felis can be completed in 12–14 days, or it can be prolonged up to a year or more: if the pre-emerged adult does not receive an emergence stimulus, it may remain quiescent in the cocoon (Fig. 5.1c) until a suitable host arrives and pupae have been recorded as lying dormant for up to 2 years until favourable conditions occur. However, under most occupied household conditions, nearly all cat fleas will complete their life cycle within 3–8 weeks. As with immature life stages, survival of adult fleas is highly de- pendent on temperature and humidity. One study has shown that, in moisture-saturated air, 62% of adult C. felis survived for 62 days, whereas only 5% survived for 12 days when main- tained at 22.5°C and 60% relative humidity (RH). It is unlikely that adult or immature fleas in the premises can survive during winter in northern temperate regions. It has also been shown that no life cycle stage (egg, larva, pupa, or adult) can survive for 10 days at 3°C (37.4°F) or 5 days at 1°C. Where do fleas hide and when are they a problem? It is important to realize that any adult fleas seen on a pet represent the ‘tip of the iceberg’ and that large numbers of immature fleas are likely be abc Fig. 5.1.  (a) Cat flea, Ctenocephalides felis. Flea mouthparts are adapted for sucking blood. In cat flea, the first two cheek comb spines are about the same length, whereas in dog flea, Ctenocephalides canis, the front-most spine of the cheek comb is shorter than the second spine. (b) Flea pupa. (c) Flea cocoon. 65

Parasites and Pets: A Veterinary Nursing Guide undergoing covert development, sometimes well away from the pet. Newly emerged fleas, in carpets or from outdoors, will bite most animals, including humans, if their preferred host is scarce, though they will not persistently infest humans. Because C. felis is not highly cold tolerant, it has been postu- lated that in cold climates it survives in the urban environment, as adults on untreated dogs and cats or on small wild mammals. Once on a host, C. felis initiates feeding within seconds to minutes. In one study, approximately 25% of fleas were blood-fed within 5 min; and in another, the volume of blood consumed by fleas was quantifiable within 5 min. Mating occurs on the host after feeding and can occur within 8–24 h. When fleas that have been on a host for several days are removed, they die within 1–4 days. Experimental work has shown that when cats are allowed to groom freely, they will ingest or groom off a substantial number of fleas in a few days. When cat fleas were allowed to feed for only 12 h and then removed from their host, 5% were still alive at 14 days. This is of particular importance, because one study showed that when cats were housed adjacent to each other but physically separated, 3–8% of the fleas moved from one cat to another. However, when cats were housed in the same cage, 2–15% of the fleas transferred. Therefore, it is possible for a few adult fleas to transfer from one host to another but it is far more likely that most flea infestations originate from previously unfed fleas emerging from environments that have supported development of immature life stages. C. felis is referred to as the cat flea because it was first described from a cat, but it is actually able to infest approximately 50 species of animals. Cat fleas exhibit an extremely prolific reproduction and, as a result, environmental infestation is difficult to control, taking a minimum of 90 days to eliminate indoor infestations. If outdoors (e.g. inside kennels), there are additional problems. An infestation in the home may not be obvious until the third generation of fleas has developed. What are the differential diagnoses for flea infestation and how can a flea infestation be confirmed? The most likely differential diagnosis for C. felis (cat flea) infestation in- cludes Sarcoptes scabiei (scabies mites), Otodectes cynotis (ear mite) in se- vere infestions, Trichodectes canis (lice), Cheyletiella yasguri (dog fur mite, or ‘walking dandruff’), dermatitis secondary to infection or allergic skin disease such as atopy. A coat brushing with a flea comb or adhesive tape impressions will reveal flea dirt as black specks, flea eggs as white specks, or adult fleas. Viewing these findings under the microscope will confirm flea life stages. Also, a wet paper will turn red due to the blood content in the flea faeces if combings are placed on the surface. To investigate other 66

Parasites of the Skin and Muscles causes of pruritis, such as mange mites, repeated skin scrapes will be re- quired to examine for the burrowing species S. scabiei, which can be dif- ficult to reveal. An aural swab may be used to make a smear to be viewed microscopically for O. cynotis, which may have spread to the body, and for bacteria and yeast. If the owner has developed pruritic skin lesions, as hap- pens with flea bites, other ectoparasites have to be excluded. If lesions are most often seen on the arms where the pet has been held, this could be due to Cheyletiella spp. or Sarcoptes, both of which are zoonotic, with the latter a cause of serious mange in dogs but very rarely associated with cats. If the owner has a history of a series of bites around the ankles, this indicates that the infestation is coming from inside the home – from carpets, for example. Bites around the waist indicate flea pupae hatching from the couch or other soft furnishings when the owner is seated. Some people are less sensitive to bites than others, so if the owners have not noticed bites, this does not rule out an internal infestation. What kind of diseases can fleas transmit? Flea-borne bacterial infections  Fleas serve as the vector of microbial agents, some of which may affect humans. Bartonella henselae is the causative agent of cat scratch disease (CSD) and can cause flu-like symptoms in humans and bacillary angiomatosis in immunodeficient patients. Other blood-borne pathogens that have been isolated from fleas include Rickettsia felis (agent of cat-flea rickettsioses) and Haemoplasma spp., which cause anaemia in cats. Rodent fleas can also transmit bubonic plague (Yersinia pestis) and murine (endemic) typhus (Rickettsia typhi). Flea-borne intestinal helminthiasis  Ctenocephalides fleas act as the intermediate hosts for the tapeworm of dogs and cats, Dipylidium caninum. Adult D. caninum excrete gravid proglottids (containing packets of eggs) in the environment, on which flea larvae feed. D. caninum larvae then hatch and migrate into the body of the flea larvae; and following metamorphosis, the infective cysticercoid stage is present in the adult flea. Dogs or cats become infected when they self-groom and ingest infected adult fleas (i.e. containing cysticercoid). Animals infected with D. caninum may have up to 130 adult tapeworms, because larval fleas can ingest whole worm packets, resulting in the development of multiple cysticercoids per flea, and each cysticercoid will lead to the development of an adult tapeworm. Hence, it is essential to control fleas in order to prevent D. caninum infection in dogs and cats. In rare cases, D. caninum can also affect humans, particularly children. Fleas can also act as the intermediate host of Hymenolepis nana and the non- pathogenic subcutaneous filarid nematode of dogs, Acanthocheilonema (Dipetalonema) reconditum. 67

Parasites and Pets: A Veterinary Nursing Guide What is flea allergy dermatitis? Flea allergy dermatitis (FAD) is the most common dermatological disease of dogs and a major cause of feline miliary dermatitis. It is an immunological disease in which a hypersensitive state is produced in a host, resulting from the injection of antigenic material from the salivary glands of fleas. The way in which an animal responds to FAD varies between species; for example, cats typically develop military dermatitis. In dogs, the dermatitis is typically confined to the dorsal lumbosacral area (Fig. 5.2). What flea control questions and problems might face a veterinary nurse? Firstly, armed with the above knowledge, a nurse must introduce concepts of integrated control. Integrated flea control consists of four steps to break the flea life cycle at as many stages as possible: 1.  Using a licensed product on the pet that is fully effective against adult fleas (an ‘adulticide’) and kills fleas before they can produce eggs (the repro- ductive breakpoint). 2.  Using an insect growth regulator (explained below), either directly into the environment or on the pet to break the flea life cycle. 3.  Mechanical measures such as washing bedding to at least 60°C and daily vacuuming to reduce organic matter on which flea larvae feed, as well as physically removing pupae from the environment. 4.  Education – ensuring that the client is aware of the importance of the above steps and treatment timeframes, so that client expectations of success in eliminating fleas from the household are realistic. Fig. 5.2.  A dog showing the classical skin lesion of flea allergy dermatitis. 68

Parasites of the Skin and Muscles Integrated control also involves making a decision about the choice of a product that will prevent other ectoparasitic infestations besides fleas, such as ticks. How do insect growth regulators work? Insect growth regulators (IGRs) are available for flea control. They act to inhibit insect development into the next immature life stage. For instance, they may inhibit insect chitin synthesis (a protein needed to build the insect’s larval and egg cuticle) (e.g. lufenuron). Other types mimic juvenile growth hormone levels, which would normally drop to initiate the next life stage (e.g. s-methoprene). In the case of a premises infestation, the IGRs in the flea environment will pre- vent viable eggs accumulating and hatching and will prevent larvae developing into pupae. However, there are no products available that effectively kill the pupal stage, because these are buried deep in the pile of the carpet, in cracks and crevices of the floor or within soft furnishings and are protected by their cocoons, which are further inaccessible, being covered in debris. What advice do you give to a client whose pet is heavily infested? The client’s household is likely to have an established infestation rather than, say, an externally acquired transient problem. Firstly, all pets in the household must be treated, with an approved licensed product that kills adult fleas within 24 h or less. Untreated pets must not be allowed access to the premises. In addition, all areas of the home/car/shed/caravan that the pet frequents, especially for sleeping, should ideally be treated with an IGR to help break the flea life cycle and hence reduce the time it takes to clear the infestation. Treated pets should be allowed access to all areas where they have previously been allowed as newly emerged hungry fleas will then be exposed. Owners need to be aware that pupae will continue to be a source of new fleas for at least the next 2–3months until this reservoir is naturally depleted. Advice given should include the principles of integrated control and must necessarily be tailored to suit individual situations. During a household flea infestation, a client changes to a different flea product due to efficacy concerns and this second product appears to be effective. How might this be explained? There are no insecticides that kill flea pupae. The so-called ‘pupal window’ period is the time it takes for fleas to hatch from pupae already in the house- hold, which is usually 2–3 months but can be much longer, depending on temperature, relative humidity and availability of hosts for new fleas. Pupae can lie dormant for up to 2 years if left undisturbed in cool climates. If clients 69

Parasites and Pets: A Veterinary Nursing Guide have not been informed about this ‘flea reservoir’ they will typically get very frustrated with whichever product they were first dispensing and may choose to swap products. By the time this happens, the pupal window may have been coming towards its natural end and the infestation was clearing anyway. It is therefore advisable to pick a licensed product and keep using it at recom- mended intervals until the infestation comes to an end and then continue to use preventive treatments all year round. Why might flea control fail? Possible explanations for failure include that the dog and cat may not have received the topical adulticide application at the recommended treatment intervals. There may be untreated animals in the home or otherwise in con- tact, or the pet has been washed with a shampoo while using a spot-on product that is not absorbed systemically. The presence of adult cat fleas despite use of effective adulticide treatment may be due to a lack of compli- ance or the insecticide may not have been administered correctly. Resistance to flea products in the domestic setting has never been documented. Fly Strike What is fly strike in rabbits? During the summer months, emergency clinics see a considerable increase in the number of fly strike cases in pet rabbits. Fly strike is a devastating condition caused by the fly Lucilia sericata, or green bottle fly, the same species that causes the common fly strike problem in sheep. These flies are attracted to damp fur soiled with urine or soft faeces. Each fly can lay up to 200 eggs on the skin at the rear end of an animal, which within hours, hatch into maggots and grow by feeding on the flesh of the rabbit. The maggots can very quickly eat away large areas of tissue around the bottom, tail, scent glands, belly and back and affected rabbits are quite literally ‘eaten alive’. What are the symptoms of fly strike? Initially, the pet may seem quiet, so it is important to check the rabbit’s fur daily for any signs of maggots. As the maggots grow and eat away more sur- face area of the skin, severe shock develops, eventually leading to collapse and death. How do you treat fly strike? If veterinary help is sought early, the patient can be saved by receiving prompt treatment comprising the removal of every single maggot (espe- cially the small ones and looking for any unhatched eggs), clipping and 70

Parasites of the Skin and Muscles cleaning debris from the fur, pain relief, topical soothing products and anti- biotics. Fluid therapy, treatment of gastrointestinal complications and syr- inge feeding may be required in more severe cases. If extensive tissue loss has occurred a rabbit may need to be euthanized to relieve suffering. What can be done to prevent fly strike? Many affected rabbits are very well looked after in general but it only takes a small amount of soiling for the flies to strike. Rabbits that cannot groom themselves effectively due to long fur, obesity, arthritis or painful teeth are at greater risk. Checking the rabbit’s bottom daily will help to detect in- festation early. Topical products containing the IGR cyromazine are also effective to prevent fly eggs from hatching. After an application, protection lasts for up to 8–10 weeks. Louse Infestations What are lice? Lice are wingless insects, flattened from top to bottom, that cling to hair or feathers of animals by means of their strong claws. Lice species can be dis- tinguished by the characteristic shape and width of their heads and there are two types, with a similar life cycle. Biting lice can generally be distinguished from sucking lice by the flattened, wide head. Sucking lice tend to have longer pointed heads and mouthparts. Biting or chewing lice belong to the order Mallophaga and feed mostly on skin debris and secretions. Those that belong to the order Anoplura feed differently – they suck blood. Female lice lay white eggs with lids (‘nits’) on the animal’s fur (Fig. 5.3a), sticking each one firmly to a hair shaft. Nymphs hatch from the eggs, feeding and undergoing three moults before becoming adults. The life cycle can be completed in 14–21 days. Transfer of lice between hosts is mainly through close physical contact between animals. The term ‘pediculosis’ is used for ab c Fig. 5.3.  (a) Louse egg ‘nit’. (b) Canine chewing/biting louse, Trichodectes canis. This louse is about 1.5 mm long, with body flattened top to bottom and a broad, round head. (c) Chewing louse of cats, Felicola subrostratus, readily identified by the unique shape of its head. 71

Parasites and Pets: A Veterinary Nursing Guide disease due to severe infestations, often associated with older animals unable to groom, those in general poor condition or those suffering from neglect. Which types of lice infest dogs and cats and how do they cause harm? Dogs may be infested with two species: the blood sucking louse Linognathus setosus and the chewing/biting species Trichodectes canis (Fig. 5.3b). Cats are infested with only one louse species, Felicola subrostratus, a chewing type (Fig. 5.3c). T. canis is the most common species on dogs; the lice are 1–2 mm in length, yellowish, and dorsoventrally flattened with a clearly recognizable round head, which is the same width as the abdomen. They attach to hair shafts typically around the head, neck, back and tail area, where they feed on dermal debris and exudates from skin lesions. Mature females lay several eggs per day and the nymphs, which resemble the adults, hatch from the eggs within 1–2 weeks of oviposition. Adults live for about 1 month and are very mobile, producing intense irritation, pruritus and scratching. Linognathus lice are much less common. They are brownish-yellow, meas- uring 1.5–1.7 mm; the head is long, narrow and pointed, significantly nar- rower than the slender and elongated abdomen. These lice feed on blood, with females laying one egg per day. Sucking lice infestations are most com- monly found on long-haired breeds, such as spaniels, basset hounds and Afghan hounds. Preferred sites for these lice include the ears, neck and back. The infestations may result in pruritus, alopecia and excoriations and se- verely infested dogs may become anaemic. F. subrostratus (the biting louse of cats) are yellow to beige and measure 1–1.5 mm. They have a distinctive triangular-shaped head and mouthparts with a median longitudinal groove to grasp an individual hair. Infestations most commonly occur on the face, back and pinnae. Long-haired breeds are more prone to severe infestations, especially under matted or neglected fur. Lice infestations in cats may result in dull and ruffled hair, scaling, crusts, alopecia and significant skin irritation leading to pruritus, dermatitis, ex- coriation and alopecia with broken hair shafts. Can owners become infested from their pets? No. Lice are species specific and so people do not become infested by lice from their pets. How do you diagnose suspected louse infestations? Close observation, brushings, hair plucks and adhesive tape strips may re- veal adult lice and lice eggs attached to hairs. All these stages are visible to the naked eye but microscopic examination will confirm their presence. 72

Parasites of the Skin and Muscles What are the general considerations for louse control? Lice infestations are frequently encountered in neglected animals, for ex- ample those subjected to overcrowding, poor sanitation or with underlying health conditions which predispose to growth of louse populations. Most healthy animals are able to tolerate lice in low numbers. When spotted, lice can be easily killed and traditional treatments have included the use of con- ventional insecticidal shampoos, sprays and powders. Biting and sucking lice infestations on dogs have been eliminated following a single topical spot-on application with 9.1% wt/wt imidacloprid. Biting lice infestations on dogs have been successfully treated following a single topical spot-on ap- plication with 10% imidacloprid + 2.5% moxidectin, 10% fipronil, or 65% permethrin. Biting lice on cats and dogs have been successfully treated with a single topical spot-on application of selamectin. Transmission is through close contact and so pets of the same or closely associated species should all be treated to avoid spread. Because there is no persistent environmental stage, lice infestations can be controlled by physical removal of lice and eggs with a nit comb. However, cats and dogs have a much greater surface area of hair compared with treating human head lice by this method and combing may unintentionally aid in the spread of the parasite if combs are not thor- oughly cleaned and all lice life stages destroyed. Do owners need to treat the environment if their pets have lice? Although there is no persistent environmental stage and the whole life cycle takes place on the pet, lice can survive in the environment for 1–2 days. If multiple pets are in a household, it is therefore worth treating bedding with a pyrethroid spray or washing at more than 60°C. It is not essential to treat the environment as long as all in-contact pets of the same species are being treated. Is there any evidence of resistance in lice to insecticides? Human head and body lice insecticide resistance is well documented and intensive treatment along with the lack of wildlife reservoir hosts (refugia) has led to widespread resistance to conventional insecticides. However, this has not been the case in cat and dog lice. Mite Infestations and Mange What are mites and what is mange? Mites are small parasitic arthropods of birds and domesticated and wild animals. They are not insects, but acarines, which are in the same class as ticks. Morphologically, therefore, parasitic mites do not have distinct body regions (as do insects) and the head and thorax are fused together, as in 73

Parasites and Pets: A Veterinary Nursing Guide ticks. Mites that cause skin conditions in dogs and cats (this has the special name, mange) are small and soft bodied and examples are Sarcoptes spp., Notoedres cati and Demodex spp. These types actually tunnel into the skin or hair follicles to lay eggs and are known as ‘burrowing mites’. There are others that feed on the skin surface and are described as ‘non-burrowing’; the dandruff mite, Cheyletiella spp., and the ear mite, Otodectes spp., are ex- amples of the latter. They feed superficially on skin and scales. Identification of mites is based on the morphology of the adults and detection generally requires skin repeat scrapings. Demodex is an exceptional mite in that it lives in the hair follicles and sebaceous glands, and in cats and dogs causes demodectic mange in susceptible animals. Cheyletiella, the ‘walking dandruff’ mite What are Cheyletiella mites and how do they complete their life cycle? Cheyletiella spp. (Fig. 5.4) are non-burrowing and live in the keratin layer of the epidermis, consuming surface debris and tissue fluids. The eggs are attached to the host animal’s hair and are smaller than the average louse egg or ‘nit’. Three morphologically similar species of Cheyletiella exist: C. yasguri in dogs, C. blakei in cats and C. parasitivorax in rabbits. Adult mites are rather large with an ovoid shape, measuring about 400 μm in length, with characteristic curved palpal claws at the head end. They move rapidly and induce bran-like exfoliative debris on the rumps and backs of animals, resulting in a ‘walking dandruff’ appearance (the colloquial name for the skin condition these mites cause). They do not burrow but pierce Fig. 5.4.  Cheyletiella, surface-dwelling (non-burrowing) mite. This mite resides in the keratin layer of the skin and in the hair coat of the host. It is referred to as ‘walking dandruff’ because Cheyletiella mites often resemble large, mobile flakes of dandruff. 74

Parasites of the Skin and Muscles the skin with stylet-like chelicerae to feed on lymph. The pre-larva, and larva, develop within the egg and moult through two nymphal stages before becoming adults. Young animals, especially when housed in cages or ken- nels, and debilitated individuals are particularly susceptible to infestation. Heavily infested dogs may have excessive shedding of hair, inflammation and hyperaesthesia of the dorsal skin. Cats are primarily affected around the head and trunk. What are the clinical features of cheyletiellosis and differential diagnosis? These are pruritus and excessive dorsal scaling, and ceruminous otitis ex- terna. Flea infestation, otodectic mange and scabies should also be con- sidered as a cause; less likely differentials include pediculosis, primary seborrhoea, malnutrition and demodicosis. Which diagnostic tests can confirm cheyletiellosis? It is best to examine debris from a coat brushing, preferably on to a dark surface, using a hand lens and examining the debris for movement. Low- power microscopic examination of superficial skin scrapings in liquid par- affin or acetate tape preparations from the skin surface may allow detection and identification of the mite, and the technique can cover large areas and improve sensitivity. Can owners become infested? Yes, all three species can cause a transient problem in humans, manifesting as papular lesions. A history of a recently introduced pet in the household may be a clue to the diagnosis. Infested pets may be asymptomatic or have a mild dermatitis, often with dry, white scales on the dorsum of the back. Affected humans may develop a more prominent dermatitis, with grouped erythematous pruritic papules; occasionally, apical vesicles, bul- lae or urticarial wheals can be noted. The rash is commonly found in areas that have been in direct contact with the source animal, such as the chest, abdomen and upper extremities. Systemic hypersensitivity to Cheyletiella blakei has been reported, with associated peripheral blood eosinophilia and joint pain. How do you treat for Cheyletiella? Currently there are no products licensed for the treatment of cheyletiellosis in either cats or dogs. Spray, shampoo or spot-on formulations containing pyreth- rins or pyrethroids are effective for treatment of cheyletiellosis on dogs; pyreth- roids should not be applied to cats. Fipronil spot-on or spray formulations have 75

Parasites and Pets: A Veterinary Nursing Guide been used for treatment of cheyletiellosis in dogs and cats. Spot-on treatment solution containing 10% imidacloprid has been shown to be effective for the treatment of canine cheyletiellosis, whereas spot-on selamectin solution has provided efficacy for the treatment of feline cheyletiellosis. The bedding and grooming equipment of infested animals should be disinfected. Demodex – the follicle mite Why is Demodex important? Demodex canis is a minute, specialized burrowing mite, with a cigar-shaped body measuring 100–300μm in length and four pairs of stout legs ending in small blunt claws (Fig. 5.5). The opisthosomal region (behind the legs) is at least one-half of the body length and has a transversely striated cuticle. Demodex mites are unusual in that they live in the hair follicles and seba- ceous glands of a wide range of wild and domestic animals, including hu- mans, but in veterinary practice they are most important as a cause of skin disease in dogs. Feline demodicosis (caused by Demodex cati or Demodex gatoi) is an uncommon parasitic disease, though disease incidence in the UK, Europe and North America is increasing. Most dogs naturally carry a small number of D. canis without displaying clinical infestation. Under certain conditions, however, the mites can cause demodicosis (red mange), Fig. 5.5.  Dog follicle mite, Demodex canis. Demodex spp. are tiny, cigar-shaped, eight-legged mites. They reside and feed in the hair follicle and oil glands of the skin. 76

Parasites of the Skin and Muscles regarded as one of the most important skin diseases in dogs. Demodicosis is more common in purebred dogs. These mites are unable to survive without their host and transmission is by direct contact. Female mites lay 20–24 eggs in the hair follicle, which develop via two six-legged larval stages followed by two nymphal stages. All stages of the life cycle may exist concurrently in one follicle and they feed head down. The life cycle is completed in 18–24 days. Transmission of D. canis from bitch to puppies occurs during the first 3 days of life through close physical contact while nursing. In their animal hosts, Demodex spp. usually cause little concern, living as a normal skin commensal. In susceptible dogs, however, for example those that are im- munocompromised, it causes serious disease presentations. How many types of demodectic mange are there? Demodectic mange has been classified in various ways depending on the clin- ical manifestations. These categories include juvenile demodicosis, adult-on- set demodicosis, localized demodicosis and generalized demodicosis. Juvenile demodicosis, which occurs in young dogs between 3 and 15 months of age, results in non-pruritic areas of focal alopecia on the head and forelimbs. The hind limbs and torso are rarely affected. The first lesions are frequently ob- served just above the eye, with small patches of depilation around the eye resulting in a ‘spectacled’ appearance. This form of the disease is self-limiting and recurrences are rare. Immunosuppressive therapy with glucocortic- oids, however, may cause deterioration leading to generalized and pustular manifestations. Adult-onset demodicosis is often associated with concurrent staphylococcal pyoderma and is a pustular form of the disease. It can be local- ized or generalized with clinical signs including erythema, pustules, crusts and pruritus. The localized form is often confined in an area of one or two paws, whereas generalized conditions include six or more localized lesions on more than two affected limbs. The skin often becomes hyperpigmented in chronic cases. The generalized form commonly develops as a consequence of an under- lying debilitating disease, such as hypothyroidism, hyperadrenocorticism, dia- betes mellitus, prolonged immunosuppressive therapy, or neoplasia, or various infectious diseases, such as leishmaniosis, which reduce the host’s immune de- fence mechanisms and are followed by a massive multiplication of mites. Does Demodex from pets have any public health impact? No. Demodex spp. are species specific. Humans have their own two species. How do you diagnose demodicosis? The diagnosis of demodicosis is based on the demonstration of large num- bers of adult mites or significantly increased numbers in the immature stage 77

Parasites and Pets: A Veterinary Nursing Guide as a proportion of adult mites. Deep skin scrapings taken from the edge of the lesions increase the chances of detecting the mites. Skin folds should be squeezed firmly to expel the mites from the depths of the hair follicles. Skin scrapings revealing low mite numbers should be considered normal hair fauna. Mites may also be detected by plucking hair samples for microscopic examination of the follicles. How do you control demodicosis? Localized demodicosis usually resolves spontaneously within 6–8 weeks, with or without the use of an acaricidal treatment. Treatment of generalized demodicosis is challenging and difficult and frequently requires extended and intensive therapeutic intervention. Amitraz, a formamidine derivative, is approved for the treatment of canine generalized demodicosis, applied as a dip at the rate of 250 ppm (0.025%) of active drug. About three to six applications that are 14 days apart may be necessary. Treatments should be preceded by a benzoyl peroxide shampoo to remove crusts and debris and to flush the follicles, allowing for better penetration of the acaricide. Treatment with amitraz washes carries a high success rate, though relapses after treat- ment are common. Some dogs will suffer skin reactions from treatment and its use is contraindicated in diabetic patients and Chihuahuas. Protective clothing is required for the person who administers the product and washes should be applied in a well ventilated room. Human diabetics and asthma sufferers should not apply the product. Macrocyclic lactones have also been used successfully for treatment of generalized demodicosis. The spot-on formulation containing 10% imidacloprid + 2.5% moxidectin, applied topically at the recommended rate of 0.1 mg/kg, two to four times at 4-week intervals, provided clinical improvement, though weekly adminis- tration is also licensed and often required for clinical improvement to occur in more severe cases. Milbemycin oxime administered orally with dosages ranging from 0.5 to 2.2 mg/kg/day and treatment durations ranging from 9 to 26 weeks have been reported to be effective, but it is not licensed for this purpose in all European countries. Oral doses of ivermectin at 300 to 600 μg/kg/day with treatment duration extending 1 month beyond negative skin scrapings have also been effective but are not licensed in Europe or North America for this purpose. The extra-label use of avermectins or milbemycins for the treatment of ca- nine demodicosis should be approached with caution, especially for breeds with known sensitivity to these compounds. The isoxazolines are a recently developed class of insecticide for use against fleas and ticks and have also demonstrated excellent efficacy in the treatment of demodicosis. While cur- rently an off-label use, it is likely that these products will become licensed 78

Parasites of the Skin and Muscles for the treatment of demodicosis in the near future. While a dog is being treated for demodicosis, skin scrapings should be collected every 2–4 weeks, preferably from the same locations at each sampling site (at least one sample from the head and foreleg, respectively), undergoing microscopic examin- ation for mites to monitor treatment progress. The total number of detect- able mites, the ratio of live to dead mites and the ratio of adult Demodex mites to those in immature stages should be determined. These ratios can then be used to determine the success of the initial treatment. A quantita- tive reduction in the numbers of adult and immature mites or an abundance of dead mites is an indication of a successful healing process. A continued presence of numerous mites and a comparatively large number in the im- mature stages relative to adult mites may indicate further progression of the disease. Female dogs with generalized demodectic mange or a history of demodectic mange should be spayed, because the condition may worsen or relapse during oestrus or pregnancy and because of the inheritable predis- position of the disease. Notoedres – a mange mite of cats What is the importance of Notoedres cati? Notoedres cati is similar in appearance to the scabies mite, Sarcoptes sca- biei, and is the cause of face or head mange in cats, but other small ani- mals such as pet rats and hedgehogs can also be affected. Females are about 230–300μm in size, whereas males are smaller. Notoedric mange manifests as alopecia and marked hyperkeratosis around the head and ears, with abundant epidermal scaling. Mites are transferred through direct contact and from infested females to kittens. Mites are identified by the round ap- pearance, concentric striations on the dorsal cuticle and small stumpy legs. Very oddly, close examination will reveal that the anus is situated dorsally, i.e. on the back of the mite. Otodectes – the ear mite What is ear canker mite? Otodectes cynotis (ear mite or ear canker mite) occurs worldwide in the external auditory canal of domestic dogs and cats; ferrets and other car- nivores can also be affected. The mite is about 400 μm long, with a body flattened top to bottom and four pairs of long legs (Fig. 5.6). The epimeres (folds of cuticle) extending from the head region to the bases of legs 1 and 2 are joined. All developmental stages are found on the surface of the external ear canal, without being buried in the skin. The mite feeds on desquamated epithelial cells and aural exudates, but occasionally the mites pierce the skin to feed on blood, serum or lymph. 79

Parasites and Pets: A Veterinary Nursing Guide Fig. 5.6.  The ear mite, Otodectes cynotis. This mite is about 0.4 mm long, with a body flat- tened top to bottom and four pairs of long legs. The male has a sucker on the end of each leg, while the female has suckers on only the first two pairs of legs. Living mites appear as small white organisms that can be seen moving within the ears or on swabs of deteritus removed from the ears. What is the significance of ear mites? This is a common mite infestation and the clinical importance of O. cynotis in pets is very high. O. cynotis is the cause of 50% of otitis externa cases in dogs and 85% of cases in cats. Mites are very annoying to cats: they cause severe irritation and thick, red crusts in the external ears. Eventually, infested ears droop and show a discharge. If the infestation is untreated, infection may spread from the outer to the inner ear, with possible serious bacterial involvement. The tympanic membrane may be perforated and ot- itis media and nervous signs (e.g. convulsions) can develop. How do you control O. cynotis? The ear canal of infested animals should be flushed and cleansed with a mild ceruminolytic agent. Traditional treatments have included using pre- parations of acaricides or mineral oil instilled directly into the ear canal. Frequent reapplications may be required. An otic suspension containing 0.01% ivermectin controls adult mites and also prevents the hatching of larvae from eggs. Systemic products providing extended residual activity 80

Parasites of the Skin and Muscles are highly efficacious and convenient to apply. Topically applied imidaclo- prid + moxidectin solution is efficacious for treatment of otodectic mange in cats and topically applied selamectin solution is efficacious for the treat- ment of otodectic mange in cats and dogs. When a case of otoacariasis is confirmed, all dogs and cats in the household having direct contact should be treated. In addition, grooming equipment and bedding should be disin- fected, because mites are able to survive for a period of time off the host. Sarcoptes scabiei – the itch mite What is the life cycle and biology of S. scabiei? S. scabiei, a burrowing itch mite, is the cause of sarcoptic mange or sca- bies and is able to infest a range of mammals. For small animal veterinary practices, it is sarcoptic mange in dogs that is of greatest concern. These mites have different degrees of host adaptation. Each subpopulation may be highly adapted to a particular host, so some strains may not easily infest a different species. Only one true species is recognized, but the mite often has ‘var.’ after the species name, which is an abbreviation for ‘variety’. Hence, the mite found on dogs is often referred to as S. scabiei var. canis. Sarcoptic mange is rare in cats. Adult female mites are 300–600 × 250–400 μm, whereas males measure 200–240 × 140–170 μm. These mites are unmistakeable in skin scrapings, being round, with the stumpy legs barely projecting beyond the body margins; the head is round but the main identification criteria are the scales and pegs or spines on the dorsal surface of the mite, which no other mange mite possesses (Fig. 5.7). The life cycle of S. scabiei var. canis takes place exclusively on the dog, passing from egg to larva and through two nymphal stages in 2–3 weeks. After mating on the skin surface, the females burrow into the epidermis, making tunnels up to 1 cm long that are parallel to the surface. After a mat- uration phase of 4–5 days, the females deposit one to three oval eggs daily into these tunnels for about 2 months. The six-legged larvae hatch 3–4 days after oviposition and most of them crawl from the burrows to the skin sur- face, though some remain in the tunnels, where they continue to develop. The larvae moult first to protonymphs, then to tritonymphs and then to adults. They feed on damaged skin and tissue fluids. After mating, the newly developed males die, whereas the adult females look for a suitable site on the host for burrowing and subsequently depositing their eggs. The total egg-to-adult life cycle typically requires 17–21 days but may be as short as 14 days. Mites may survive off the host 2-3 weeks in sleeping areas and on grooming equipment, which should also be considered as potential sources of contamination. 81

Parasites and Pets: A Veterinary Nursing Guide Fig. 5.7.  The burrowing itch mite, Sarcoptes scabiei. Adult female Sarcoptes have triangular spines on the dorsal surface of the body. What is the clinical presentation of sarcoptic mange? Sarcoptic mange often begins on relatively hairless areas of skin on the head, with frequent distribution to the lower abdomen, chest and legs. The ears are almost always affected, particularly the inside of the pinna, as is the lat- eral aspect of the elbow. Lesions consist of follicular papules, yellow crusts of dried serum and excoriations from scratching due to intense pruritus. Secondary bacterial infections are frequent complications. The lesions usu- ally spread rapidly, sometimes covering the entire body. The affected sites also display alopecia caused by self-inflicted trauma. Chronic cases result in thickening of the skin with hyperkeratosis, wrinkling and hyperpigmen- tation. In the most seriously affected skin areas, histopathological examin- ation indicates severe chronic inflammation of the epidermis, with variable hyperkeratosis and parakeratosis. Despite obvious clinical lesions and in- tense pruritus, a diagnosis is often difficult. Dogs infested with these mites frequently display a ‘pinnal–pedal’ scratch reflex. How are the mites detected? Direct parasite detection should be performed with microscopic examination of skin scrapings taken from the edges of the lesions adjacent to intact tissue, i.e. not from open wounds or chronically inflamed excoriations. The preferred 82

Parasites of the Skin and Muscles areas for obtaining skin scrapings are those covered with clearly visible raised yellowish crusts and papules. The accuracy of this diagnostic procedure de- pends on the number of examined skin scrapings and it is advisable to take at least ten scrapings per dog, though mites may not be found in approximately 50% of cases and diagnosis can be based on clinical manifestations and re- sponse to treatment. Unlike Demodex spp., the presence of a single mite is significant. An ELISA that detects Sarcoptes is also available. Can other parasites cause skin thickening (hyperplasia)? A hyperplastic response of the epidermis to arthropod infestation is a relatively common feature in a variety of mite, louse and flea infestations. Surprisingly, this same hyperplastic epidermal response may be elicited by parasites of a completely different phylum. For example, the nematode free-living parasite Pelodera strongyloides produces a nearly identical hyperplastic skin response when it opportunistically invades hair follicles in dogs, cattle, horses or hu- mans. Generally, this skin invasion occurs when the host is lying in damp or filthy bedding and the skin is moist for prolonged periods of time. Initially a neutrophilic folliculitis develops, but then as the host self-traumatizes its skin, the same proliferative hyperkeratotic lesions as seen in sarcoptic mange will be apparent. Lesions develop as lichenified skin, with scaling, crusting and alopecia. Recently, a case of dual infection with both Sarcoptes and Pelodera in a wild black bear was reported, and the overall gross dermal le- sions were indistinguishable from Sarcoptes alone. The skin appears to have a limited repertoire of patterns of inflammatory response, and self-trauma due to pruritis is a common manifestation of many ectoparasitic conditions. How do you control this mite and treat the condition? The coat should be clipped and crusty lesions and scale should be removed with an antiseborrheic shampoo. Traditional treatments have included the use of an acaricidal dip, such as lime sulphur, repeated weekly. Fipronil (0.25%) spray treatment (Frontline Spray, Merial) has been used successfully as an adjunct in treating sarcoptic mange alongside macrocyclic lactones. The preferred method of treatment includes the use of systemic macrocyclic lactones. A number of macrocyclic lactones have been demonstrated to be efficacious against sarcoptic mange, including monthly administration of selamectin or moxidectin (two to three treatments, 30 days apart, licensed in Europe and North America) and milbemycin (weekly treatment for 2 weeks, licensed in some European countries but not the UK). The isoxazolines have also been shown to be highly efficacious with one (sarolaner) being licensed and others likely to follow. All dogs having contact with infested dogs should be treated. Because mites are able to survive off the host, potential sources of contamination should be disinfected, including bedding, brushes and combs. 83

Parasites and Pets: A Veterinary Nursing Guide Trombicula What is the Trombicula spp. mite (‘chiggers’, ‘Harvest mite’ or ‘Berry bug’)? Cats and dogs are frequently infested on a seasonal basis with mites of the family Trombiculidae, more commonly known as ‘chiggers’ or ‘harvest mites’ (Fig. 5.8). Trombiculosis is highly unusual in that it is the larvae that cause the problem as they feed; the adults and nymphs are free-living pred- ators of soft-bodied insects. The six-legged larvae are orange-red or yellow and measure 200–300 μm and are strongly seasonal in activity, generally encountered in late summer or autumn. At these times of year the larvae hatch from eggs on the ground, climb on vegetation and wait for passing hosts, in a similar way to some tick species. They are likely to be found on the ears, eyes, nose or other areas of thin skin, including the abdomen and regions between the toes. They usually occur in large clusters, easily spotted (although small) because they are orange. The larvae pierce the superficial epidermal layers with bladelike chelicerae to inject salivary gland enzymes into the skin. They then feed on liquefied tissues, body secretions and blood. After feeding, the engorged larvae drop to the ground to continue their de- velopment. Although only on the animal for a day or two, infestations often Fig. 5.8.  Harvest mite, Trombicula (Neotrombicula) autumnalis. The six-legged chigger larva is 200–400 μm in diameter. The body is rounded and covered with tiny hairs, giving this mite a velvet-like appearance. 84

Parasites of the Skin and Muscles cause intense pruritus, erythema, excoriations and alopecia. Different re- sponses to the infestations may be due to individual hypersensitivity reac- tions to the mites. How do you prevent infestations of Trombicula spp? This is rather difficult. Infested animals generally have a history of roam- ing through woods or fields in late summer. Topically applied fipronil and selamectin have been used successfully to treat trombiculosis in cats and dogs, and topical pyrethroid + pyriproxyfen formulations have been used to control these mite infestations on dogs. Traditional acaricide and insecti- cide formulations, including dips, sprays, powders and shampoos, have been used to treat and control these infestations. Tick Infestations What are ticks? Like mites, ticks are acarines, not insects, having eight legs in the adult stage (insects, like lice and fleas, have six). Ticks are obligate blood-suckers and im- portant vectors of diseases. There are two tick families of veterinary import- ance: the Argasidae (soft ticks) and Ixodidae (hard ticks). In Europe and North America, the most important tick species affecting dogs and cats (and also biting people) belong to the Ixodidae. Hard ticks are characterized by a dorsal shield (scutum) and a ‘false’ head (the basis capituli), which is actually the head fused with the thorax and which bears the palps. Palps are sensory in function and flank a toothed probe – the skin attachment structure, the hypostome. Some species are colourful and have eye spots on the scutum and indentations on the posterior margin, like the crust of a pie, called festoons. All these features can be used to aid identification, which is clinically important since certain no- torious tick species are known vectors of serious pathogens and it is desirable to identify them, which can aid disease prognosis and help in surveillance. How do ticks feed? In order to feed, a tick locates a passing host by waving its front legs, a be- haviour called ‘questing’. The legs bear sensory organs called Haller’s organs and can detect carbon dioxide and host kairomones. Ticks pierce the skin with their chelicerae and insert the hypostome. A secretory substance holds the hypostome in place and copious amounts of saliva are injected into the host. In addition to water, the saliva contains anticoagulant and immuno- modulatory substances. The host may develop a localized reaction to the tick bite and there may be subsequent bacterial infection of the lesion. It should be noted that if a tick is forcibly removed the mouthparts may remain embedded and this may result in a foreign body reaction. Infestation with 85

Parasites and Pets: A Veterinary Nursing Guide larvae or nymphs may go unnoticed, as these immature tick stages are small. Adult ticks, particularly engorging females, are most readily seen and may be of concern to owners. Understanding how ticks feed is important in under- standing disease transmission. What is the biology and significance of Ixodes ricinus and other species in the UK? A number of tick species regularly attach to dogs and cats in the UK and countries of northern Europe but the most common is Ixodes ricinus, the sheep tick (Fig. 5.9a). I. ricinus is reddish brown, approx 4 mm in size when unfed, and pasture, woodland and scrub are all habitats for this species. Ticks that commonly occur in temperate climates all have a three-host life cycle: the larvae (Fig. 5.9b) feed on a host, drops off and moult to the nymph; the nymph feeds on another host and drop off to moult to an adult. All three stages at- tach to a different host at each feed. The immature stages feed on small mam- mals for 2–4 days but adults attach to larger hosts such as roe deer, which are increasing across Europe. Having mated while on the host, adult females feed for up to 10 days (usually 5–7 days); the large fed female tick then detaches and lays several thousand eggs in the environment before dying. The duration of the life cycle is highly dependent on environmental conditions, I. ricinus taking 3 years in the UK and Ireland to complete its life cycle (each stage feeds once per year) whilst taking only a year in Mediterranean countries. Cats and dogs become infested when they enter tick habitats and are then at risk of tick-borne diseases (TBDs). Increasing tick populations and TBDs are an emerging problem in the UK and Europe due to factors such as climate change, increase in woodland plantation, set-aside areas and increases in deer populations (an excellent feeding/maintenance host). Dermacenor reticulatus is another important species found in the UK and Europe and it also transmits Babesia canis, recently shown to be endemic in Essex, UK. a Female Male Nymph b Fig. 5.9.  (a) Ixodes ricinus adult versus nymph. (b) Ixodes ricinus larva. 86

Parasites of the Skin and Muscles What is tick-borne encephalitis (TBE)? European TBE is transmitted by I. ricinus and I. persulcatus ticks present in forest and mountainous areas in western and central Europe. TBE is endemic in Austria, Belarus, Croatia, the Czech Republic, Estonia, Germany, Hungary, Latvia, Lithuania, Poland, western Russia, Slovakia, Slovenia, Switzerland and Ukraine. TBE does not occur in the UK but very occasionally (less than one per year) cases may be imported by UK travellers who have been to en- demic areas. The majority of infected individuals do not have any symptoms, with the ratio of asymptomatic to symptomatic infection approximately 250:1. Most people with symptoms recover. However, up to one-third can suffer long-term complications due to the encephalitis. Treatment of those infected with TBE is supportive only. There is an effective vaccine available. What is the significance and life cycle of brown dog tick, Rhipicephalus sanguineus, in Europe? This species is a rarity in the UK but common in southern Europe and the USA. Infestations do arise from time to time in the UK, however, usually as a result of imported dogs. This tick is very different from I. ricinus, being adapted to living indoors, and may be found on dogs living in urban and rural environments. All stages feed mainly on dogs, or occasionally other hosts. It is a three-host species like I. ricinus. The fully fed females drop off at night and after a period of time will deposit thousands of eggs in crevices, cracks in dog kennels and under floor boards. Huge numbers of ticks can infest a single dog but most ticks are in the environment. The number of generations per year varies from region to region across Europe. Rhipicephalus sanguineus (Fig. 5.10) occasionally establishes in UK homes following dog travel abroad. Numbers increase quickly in warm rooms (e.g. kitchens) with untreated dogs. Global warming might prompt the establishment of populations in previously (largely) free areas, such as southern UK where temperatures just support the life cycle. The species is of great importance in southern Europe and indeed worldwide, as vector of pathogens such as Babesia canis and Ehrlichia canis. What are the important tick species affecting dogs and cats in North America? The tick species that most commonly infest dogs and cats in North America are Amblyomma americanum (Lone Star tick), Amblyomma maculatum (Gulf Coast tick), Dermacentor occidentalis (Pacific Coast tick), Dermacentor variabilis (American dog tick), Dermacentor andersoni (Rocky Mountain wood tick), Ixodes pacificus (western black-legged tick), Ixodes scapularis (black-legged tick), Otobius megnini (a soft tick, the spinose ear tick) and Rhipicephalus sanguineus (brown dog tick). 87

Parasites and Pets: A Veterinary Nursing Guide Fig. 5.10.  Dorsal view of Rhipicephalus sanguineus. Also known as the brown dog tick or kennel tick. It is generally found in sheltered areas where climatic conditions remain relatively con- stant. Large concentrations of populations are found mainly in warm and moist environments. How important is Amblyomma in North America and what are the associated pathogens? A. americanum (Lone Star tick) is named for the characteristic and easily recog- nizable single white spot that occurs on the dorsal shield of the female. A. ameri- canum has long palps, a long hypostome, eye spots and festoons. This tick occurs most commonly in woodland habitats with dense underbrush. Substantial refor- estation over the past century, in urban and rural habitats, has provided increased areas of habitat for white-tailed deer and for survival and expansion of A. amer- icanum. The white-tailed deer is considered a preferred host for A. americanum and all life stages will feed on it. Many other animals can be parasitized by this aggressive tick and immature stages can be found on various ground-dwelling birds and numerous mammals such as red fox, rabbits, squirrels, raccoons, dogs, cats, coyotes, deer and humans. Because all life stages can parasitize dogs and cats, A. americanum could be encountered on pets 8–9 months out of the year. Once hosts are acquired, larvae and nymphs engorge over a period of 3–9 days; adults typ- ically engorge within 9 days, but may take up to 2 weeks to do so. As with most ticks, peak seasonal activity can vary widely by geographical region. Similar to other ixodid ticks, unfed adults may survive for prolonged periods (> 400 days) if hosts are not available. In temperate climates, the life cycle often takes 2 years to complete, whereas in warmer coastal climates it can be completed within 1 year. A. americanum is considered a major vector of animal and human patho- gens, including Ehrlichia chaffeensis (causing human monocytic ehrlichiosis) and Ehrlichia ewingii. The Lone Star tick can also transmit Borrelia lone- stari and has been implicated in the transmission of Francisella t­ ularensis (causing tularaemia). The Lone Star tick has also recently been d­ emonstrated 88

Parasites of the Skin and Muscles to be a competent vector of Cytauxzoon felis, the highly pathogenic and usually fatal protozoan parasite of cats. Another Amblyomma species, A. maculatum, transmits Hepatozoon americanum, the aetiological agent of American canine hepatozoonosis. The transmission of this disease is unique, in that dogs must ingest the tick to become infected. A. maculatum has also been documented to cause tick paralysis. What is the life cycle and importance of Dermacentor in North America? Dermacentor variabilis is an ornate (i.e. has a patterned scutum) ixodid tick. The scutum, which covers the entire dorsal surface of the male and the anterior one-third of the unengorged female, is covered with metallic grey-white markings. It also has festoons on the posterior abdomen, eye- spots and short palpi. Dermacentor spp. are one of the most widespread and common ticks infesting dogs and cats in North America. They commonly occurs in grassy meadows, young forests and along roadways and trails. Common hosts for adult D. variabilis include cats, dogs, cattle, horses and other large mammals, including humans. Fully engorged D. variabilis fe- males drop from their hosts within 4–10 days and deposit 4000–6500 eggs. The life cycle can be completed in 3 months in the southern USA but it may take up to 2 years in more northern climates. These ticks may carry a number of diseases that are readily transmitted when an infected tick feeds on a dog. These include Lyme disease, ehrlichiosis, anaplasmosis, Rocky Mountain spotted fever (RMSF) and babesiosis. Should the dog’s owner be concerned if bitten? The dog is the preferred host of the adult D. variabilis, though this tick species feeds on many large mammals, including humans. This tick species is known to transmit RMSF and tularaemia to humans. It may also induce tick paralysis by elaboration of a neurotoxin that induces rapidly progressive flaccid quadriparesis. What are the important Ixodes species in North America? Ixodes scapularis, the black-legged tick (deer tick or Lyme disease tick), is an inornate tick without eyes or festoons. I. scapularis is widely distrib- uted in at least 35 states in the eastern and central USA. It is also located in central and eastern Canada. Similar to A. americanum, the distribution of I. scapularis correlates with the distribution and abundance of white-tailed deer. Exclusion of deer dramatically decreases I. scapularis populations. The white-footed mouse (Peromyscus leucopus) is of particular importance in the tick’s life cycle and disease transmission, because it serves as a host for larval I. scapularis and it is a major reservoir of Borrelia burgdorferi. I. scapularis is the vector of B. burgdorferi (causing Lyme disease) in the 89

Parasites and Pets: A Veterinary Nursing Guide central, upper mid-western, and north-eastern USA; it is also the vector of Anaplasma phagocytophilum (causing human granulocytic ehrlichiosis) and Babesia microti (causing human babesiosis). I. scapularis may also cause tick paralysis. The western black-legged tick, I. pacificus, is morphologically similar to I. scapularis. It is the vector for B. burgdorferi and A. phagocy- tophilum in the western USA. I. pacificus ticks are distributed from Mexico to British Columbia, with localized populations in Utah and Arizona. Is Rhipicephalus sanguineus important in America? Yes, indeed worldwide. R. sanguineus (brown dog tick) is reddish brown and inornate, and has a hexagonally shaped basis capituli (false head). Eyes and festoons are present. These features distinguish it from Ixodes spp. R. sanguineus is the only tick that infests human dwellings and kennels in North America. It persists in temperate regions by inhabiting kennels and homes. The life cycle may be completed in as little as 63–91 days. This re- sults in a rapid increase in tick populations and it can make infestations of homes or kennels extremely difficult to eradicate. R. sanguineus is the vector of Ehrlichia canis (causing canine monocytic ehrlichiosis) and Babesia canis (causing canine babesiosis). Also, it may transmit Anaplasma (formerly Ehrlichia) platys and Babesia gibsoni. Recently, in the south-western USA, this tick was identified as a vector for R. rickettsii, the causative agent of RMSF. What environmental control strategies can be implemented for R. sanguineus infestations? Successful strategies for brown dog tick control include appropriate use of en- vironmental acaricides (i.e. synthetic pyrethroids) behind, under and around cages and in cracks and crevices in floors, walls and ceilings. Including the ceilings is particularly important, because brown dog ticks are inclined to climb upwards in indoor environments. Application of environmental tick control products should be performed by professional pest control specialists. It is also prudent to limit access to crawl spaces under homes, decks and out- buildings, to discourage visits by wildlife. Product properties or issues to be considered when designing regimens for successful tick control include num- bers and species of ticks in the pet’s environment, expected level of exposure to ticks, prevalence and spectrum of tick-borne diseases and severity of reac- tions to tick bites. Several published studies suggest that available tick control products can aid in the prevention of transmission of vector-borne diseases. How did ticks become efficient disease vectors? Ticks are notorious vectors of numerous infectious (bacterial, protozoal and viral) diseases in animals and humans. Many of the TBDs can cause 90

Parasites of the Skin and Muscles ­significant economic consequences and are challenging to control. The im- portant role of ticks in disease transmission is reinforced by the fact that ticks have a worldwide distribution, can adapt to diverse ecological niches and feed for extended periods of time and on a variety of vertebrate animals as they develop from juveniles to adults. Ticks’ salivary glands play a major role not only in pathogen transmission and establishment, but also in the secre- tion of bioactive products of various critical functions, such as anti-haemo- static, anti-inflammatory and immunosuppressive. Ticks have a long, slow life cycle that takes several years in temperate climates. Because of this lon- gevity, ticks can carry infectious organisms acquired from a huge range of wildlife hosts, over prolonged periods of time, thus not only acting as vectors but also serving as reservoir hosts for the pathogens they transmit. Some pathogens, like Babesia spp., persist in tick populations by passing from the adult tick into the eggs (transovarial transmission), an important epidemio- logical concept. Ticks can also benefit from the pathogens they carry. For instance, the presence of the bacterium Anaplasma phagocytophilum in some tick species increases the ability of ticks to survive in the cold temperatures by up-r­egulating an antifreeze-like glycoprotein. The increased survival of infected ticks allows the vectored pathogen to carry on in the environment. What is borreliosis? Lyme borreliosis is the most common tick-borne disease in Europe. A corkscrew-shaped gram-negative spirochete bacterium known as Borrelia burgdorferi is the pathogen causing this disease in animals and humans. Numerous clinical forms have been associated with Lyme disease in dogs. This multi-systemic disease causes fever, lameness, stiff joints, arthritis, fa- tigue, renal failure, heart disorders, meningitis and other neurological signs. Once the host contracts Lyme’s disease, urgent treatment with antibiotics is required. Doxycycline or amoxicillin is the drug of choice, with doxy- cycline preferred in patients with evidence of renal disease as it is excreted almost entirely in the faeces. It is also reported to reduce joint inflammation in some cases. However, doxycycline should not be used in very young pup- pies because it can cause teeth staining. Other drugs, such as amoxicillin, ceftriaxone and high-dose penicillin, have been found to eradicate the disease and cure Borrelia infection in mice models. Non-steroidal anti-inflammatory drugs may also be used for symptomatic treatment. The current canine vac- cine consists of killed B. burgdorferi in adjuvant. What is Hepatozoon? Hepatozoon canis can infect and cause disease in dogs worldwide. While all canine infections were attributed initially to H. canis, in 1997 a novel spe- cies, H. americanum, was identified in dogs in the southern USA. Contrary 91

Parasites and Pets: A Veterinary Nursing Guide to H. canis infection, H. americanum typically results in a severe debilitating course of illness which, in the absence of treatment, is usually fatal. What is Crimean Congo haemorrhagic fever (CCHF)? CCHF is a viral infection transmitted by Hyalomma ticks and may arrive one day in the UK, carried by migrating birds and possibly establishing with cli- mate change. It occurs in Eastern Europe and the Mediterranean. European outbreaks have also been reported in Albania, Greece, Kazakhstan, Kosovo and Turkey. CCHF is rare in travellers. However, in 1997, CCHF was re- ported in a UK traveller who had been to Zimbabwe. Symptoms are often mild, starting 1–3 days after a tick bite. Symptoms include fever, dizziness, headache, myalgia and photophobia. This can progress to haemorrhagic manifestations and death. The case fatality rate is between 20% and 35%. Treatment is supportive and there is no vaccine currently available. What is tick paralysis? Tick paralysis is not an infectious disease but is worth briefly considering, because ticks cause it and it affects dogs and cats, livestock and, in some cases, humans. This toxicosis is caused by neurotoxins produced by tick salivary glands and results in a rapidly ascending flaccid paralysis. To pro- tect against Ixodes holocyclus tick-induced paralysis, research has been dir- ected towards developing a vaccine using a recombinant inactive form of the toxin. However, other tick species, such as R. sanguineus, may also cause paralysis in dogs and thus require development of prevention measures. Why don’t dead ticks always fall off a host immediately? Dead ticks do not always fall of the host immediately because they release a cement- like substance that can take up to 5 days to dissolve, even after the tick has died. How do you remove ticks? Ticks should be removed with either a simple ‘twist and pull’ action (if using a tick hook) or a straight gentle pull (if using fine-pointed tweezers). Ticks should not be crushed, squeezed, frozen or topically treated before removal as this will lead to regurgitation of stomach and salivary gland contents, in- creasing the risk of disease transmission. To avoid squeezing and crushing, blunt-ended tweezers or fingers should not be used to remove ticks. How do you treat and prevent tick infestation? Products include fipronil and imidacloprid (with permethrin) formulations, isoxazolines or synthetic pyrethroids, permethrin and deltamethrin (dogs 92

Parasites of the Skin and Muscles only), and flumethrin incorporated into collars. Where R. sanguineus in- festation has established in a house or kennels, environmental treatment with acaricide (preferably unrelated to the treatment used on the animals to avoid possible toxicity) may be necessary. Infestation levels should be monitored and treatment continued until there are no longer signs of tick infestation, bearing in mind that some infestations may be seasonal. The newer tick (and flea) control products, the isoxazolines, include afoxolaner with a claim of kill in 1–2 days, and with 1-month duration, as a chewable tablet, with the active ingredient entering the bloodstream, not the coat. In the same class is fluralaner, which will kill ticks within 12 h, protect for 3 months (2 months for R. sanguineus) and is administered orally as above. While highly efficacious and useful in reducing disease transmission, none of these products is 100% effective, making checking pets for ticks at least every 24 h and removing any found as described also important. What should you do with the collected ticks? It is always of value to identify ticks as this provides baseline data for surveil- lance purposes (https://www.gov.uk/guidance/tick-surveillance-scheme). The collected ticks should be preserved in glass vials containing 70% ethanol with a few drops of glycerine to maintain the natural colour and to prevent the hardening of the sample. Then, ticks should be identified using phenotypic iden- tification keys for local tick species (e.g. http://www.bristoluniversitytickid.uk). Also, in the UK, animal owners and veterinary professionals can send ticks to Public Health England’s Tick Recording Scheme or the Big Tick Project (http://www.bigtickproject.co.uk) for proper identification of the tick species. Leishmaniosis What is leishmaniosis? Leishmaniosis is a Sandfly-borne disease of dogs caused by Leishmania spp. of the family Kinetoplastidae. Infection with Leishmania spp. can result in a spectrum of clinical diseases, dependent upon the infecting species. In Europe, three species have been reported: L. infantum, L. tropica and L. donovani. L. infantum is the only Leishmania species reported in both Old and New Worlds; it can potentially cause fatal leishmaniosis in dogs and visceral leish- maniasis (VL) and cutaneous leishmaniosis (CL) in humans. L. tropica and L. donovani occasionally cause CL and VL in humans. How many Leishmania species can infect cats? Five Leishmania species have been identified in cats: L. mexicana, L. venezuelensis, L. braziliensis and L. amazonensis in the New World, and L. infantum in both the New and Old Worlds. L. infantum is the only species isolated from cats in Europe. 93

Parasites and Pets: A Veterinary Nursing Guide What is the life cycle of Leishmania parasites? The Leishmania life cycle involves a mammalian host and a vector stage. Phlebotomine sandflies (Fig. 5.11a) of the genus Lutzomyia in the Americas and Phlebotomus in other regions of endemicity in Europe serve as vectors for Leishmania. Sandflies are the only arthropods that are adapted to bio- logical transmission of Leishmania. The sandfly injects infective promas- tigotes into a susceptible mammal during feeding. Promastigotes are then quickly phagocytized by resident phagocytes, transformed into tissue-stage (Fig. 5.11b) amastigotes, and divide through simple division in a parasito- phorous vacuole. Sandflies become infected through feeding on a host either with an active skin lesion or with parasitaemia. Parasites convert to promas- tigotes within the sandfly midgut and reproduce to high numbers in 4–14 days. These promastigotes migrate to the salivary glands, transform into in- fectious metacyclic promastigotes and await the initiation of feeding. Is there evidence of non-sandfly transmission in dogs? Ticks and fleas have been evaluated as potential vectors of Leishmania but no evidence has been shown that they have a role in natural transmission of the protozoan. Direct dog-to-dog transmission has been implicated as being responsible for transmission of infection among foxhounds in the USA in the absence of apparent vectors; however, this has not been confirmed yet by ex- perimental evidence. Transplacental transmission of infection in dogs is also possible and recently venereal transmission has also been reported in dogs. Transmission of infection by infected canine blood products has been docu- mented and is of special concern in areas where blood donors could be carriers of infection. Nevertheless, non-sandfly modes of transmission probably play only a marginal role in the natural history and epidemiology of leishmaniosis. ab Fig. 5.11.  (a) The phlebotomine sandfly, the insect vector of the protozoan parasites of genus Leishmania. (b) Leishmania amastigotes reside within infected macrophages of infected host. 94

Parasites of the Skin and Muscles How is leishmaniosis diagnosed? The diagnosis of leishmaniosis takes into account the epidemiological context, clinical signs and results of laboratory tests. Information is collected about the animal’s way of life (indoor/outdoor), history (particularly for the investigation of events that may have depressed its immune status, such as feline immuno- deficiency virus (FIV) infection, pregnancy or particular treatments such as cor- tico-therapy) and age. It is of first importance to know if the animal lives or has travelled in endemic areas. Leishmaniosis is characterized by various inconsistent and non-specific clinical signs. Furthermore, atypical forms of the disease can occur. Hence, the veterinary practitioner is most frequently led to request labora- tory tests to confirm its diagnosis. Blood, urine and tissue samples are collected for non-specific and specific laboratory tests. Infections such as feline immuno- deficiency virus or other blood infections (e.g. ehrlichiosis, hepatozoonosis, ba- besiosis) may also occur and should not be excluded before a definitive diagnosis. What are the clinical signs in dogs? Canine leishmaniosis is chronic in presentation with a variety of presenta- tions and periods of remission. Signs are due to immune complex deposition in various organs and include alopecia, hyperkeratosis, dermal ulcers, polyarthri- tis, ocular inclusion bodies, uveitis, hepatopathy, glomerulonephritis and neuro- logical signs associated with spinal and central nervous system granulomas. Peri-ocular alopecia (lunettes) are a classic sign and easily mistaken for atopy. What are the predominant clinical signs in cats? The most frequently described forms in feline leishmaniosis are cutaneous, consisting of ulcerative dermatitis, nodular dermatitis, alopecia and scaling. Animals are sometimes in poor condition with poly-lymphadenopathy, an- orexia and cachexia. Other forms of the disease such as ocular and visceral forms have been described and it is likely that new particular clinical ex- pressions will soon be described, given the recent interest in this disease in cats. Associated signs such as stomatitis and respiratory disease have also been observed. Subclinical infections may be usual in cat populations living in enzootic areas. For those animals, infection can develop into one of three patterns: progressing towards clinical disease; prolonged subclinical infec- tion; and elimination of the parasite. What are the blood and urinary changes in dogs with leishmaniosis? Non-specific laboratory tests (including complete blood count, serum biochem- ical panel, serum protein electrophoresis and urine) can lead to a suspicion of leishmaniosis and help to evaluate the physiological condition of the animal (particularly the renal function). Haematology generally shows ­regenerative 95

Parasites and Pets: A Veterinary Nursing Guide or non-regenerative anaemia, lymphopenia, monocytosis and sometimes thrombocytopenia. Urinalysis can show moderate to severe proteinuria. Which tools do you use to confirm diagnosis? Specific diagnostic tools include microscopic examination of tissue samples, culture of the parasite, serology and PCR. Cytopathology  The simplest method for the specific diagnosis of Leishmania is the demonstration of amastigotes in stained smears (Giemsa or May-Grünwald) from aspirates of hypertrophic lymph node or bone marrow. This technique offers a definitive diagnosis for a low cost and can be done quickly at veterinary clinics. However, it requires an experienced practitioner to be done properly. Cultures  Parasites can be cultivated from bone marrow, lymph nodes or cutaneous biopsies in several media, but this technique is time consuming and lacks sensitivity. Therefore, it is rarely used for diagnosis, but is very useful for the isolation and identification of the parasite species. Serology  The detection of anti-Leishmania antibodies (mainly IgG) can be performed using several techniques: agglutination tests, counter- immunoelectrophoresis, indirect immunofluorescence (IFAT), enzyme-linked immunosorbent assay (ELISA) and western blot. IFAT is widely used because it is easy to perform and offers good sensitivity and specificity. The test is genus specific, though cross-reactions may occur for individuals infected with parasites related to Leishmania (Trypanosoma cruzi or T. rangeli). All animals generally develop a humoral immune response and produce high antibody levels. However, a detectable level of antibodies in the blood may remain several months after the infection of the animal, especially for cutaneous forms of the disease. For cats particularly, the lack or low production of specific antibodies by infected animals could be related to the most common cutaneous clinical form of feline leishmaniosis rather than visceral. Polymerase chain reaction (PCR)  PCR analysis can be used to detect the presence of the parasite Leishmania and to identify the genus or the species present. PCR on blood samples is not as sensitive for detection of Leishmania infection as samples from skin, lymph node and bone marrow. Conjunctival swabs have also demonstrated high sensitivity and are relatively non-invasive. Which treatments are generally used? Treatment has a variable prognosis depending on progression of disease, hep- atic and renal function. Improvements in treatment success rates have made treatment a viable option and, as long as precautions are taken, zoonotic 96

Parasites of the Skin and Muscles risk is minimal. No treatment is currently licensed for treatment of ­canine leishmaniosis in the UK. Treatment consists of allopurinol at 10–30 mg/kg in combination with meglumine antimonite (100mg/kg intravenous or subcutaneous) every 24 h for 3–6 weeks. All antimonial compounds are nephrotoxic and to a lesser extent hepatotoxic and so prognosis is worse in patients with concurrent hepatopathy and renal impairment. Renal and hep- atic function should be closely monitored. Miltefosine (2 mg/kg every 24 h for 4 weeks) may be used instead of injectable treatments in combination with allopurinol and has the advantage in renal compromised patients of being metabolized solely by the liver. However, gastrointestinal side effects from its use are common. Treatment with allopurinol alone may be required for up to 6 months after resolution of clinical signs to prevent relapse and some patients will need to remain on the drug indefinitely. Supportive treat- ment for hepatic and renal function may also be required. Several other drugs have been evaluated in therapeutic trials with various effi- cacies, such as aminosidine, ketoconazole, pentamidine, fluoroquinolones and metronidazole. However, leishmaniosis in humans, dogs and cats should be treated with varying drugs in order to reduce the risk of parasite resistance. For this reason, treatment based on amphotericin B is only prescribed to human patients and currently forbidden to treat animals in order to limit the devel- opment of resistant strains. All those drugs are only partially effective and it is generally assumed that the success of any chemotherapeutic regimen is de- pendent on the potential immunological response of the host, particularly the cell-mediated immunity, which involves macrophages and particular cytokines, such as IFN-γ. Therapy is often followed by a clinical improvement and a de- crease in anti-Leishmania antibody titres. Treatment in cats and dogs is usually not followed by a parasitological cure and relapse of the clinical disease can occur. Follow-up of the treatment can be done by either serology or PCR. According to the clinical signs, supportive treatment for renal function, appe- tite and symptomatic treatment may also be required. The skin sores caused by cutaneous leishmaniosis can heal without any treatment but this could take months, if not years. The infection by Leishmania parasites can sometimes spread from skin to the nose and/or the mouth and develop into mucosal leishmaniosis in worst cases. Occasionally surgical intervention is required to get rid of the sores. Strict hygiene should always be advised around patients and barrier nursing should be set up for hospitalized cases. Care must also be taken with sharps, as transmission can occur via contaminated needles. Does any potential prevention system exist? Disease prevention is essential for dogs travelling to endemic countries (e.g. Albania, Croatia, Cyprus, France, Greece, Italy, Malta, Portugal and 97

Parasites and Pets: A Veterinary Nursing Guide Spain). The best way to protect animals against the disease is to prevent the vector’s bite by avoiding outdoor activities at night (because of the crepuscular activity of the sandfly), which is not always possible in en- zootic areas. Fine-mesh insecticide-impregnated bed nets help to prevent bites, as does sleeping at altitude. Recently, a vaccine for the prevention of canine leishmaniosis (L. infantum) has been produced and is licensed throughout Europe but it has not yet been tested in cat populations. The use in dogs of a licensed deltamethrin collar every 5 months or applica- tion of a permethrin spot-on preparation every 2 weeks has been demon- strated to provide high levels of protection. In cats, the use of a sustained release flumethrin collar has been demonstrated to afford some protection off-licence. Self-Assessment Questions Fleas 1. Which of the following statements relating to Ctenocephalides felis (the cat flea) is most accurate? (a) This flea is resistant to insecticidal agents currently available and high flea numbers are due to the products no longer working as they used to (b) Some cat fleas are resistant to insecticidal agents currently available but usually infestations are due to incorrect use of the products (c) There is no reported clinically significant resistance to insecticides currently available and infestations are usually due to incorrect use of the products (d) C. felis can only be found on cats and therefore dogs cannot be in- fested with the cat flea 2. Which of the following most accurately reflects the time it takes to rid a house of a flea infestation? (a) The average infestation takes 90 days to clear from a house (b) Fleas are killed within 24 h so an infestation will be cleared within 1–2 days (c) As the flea life cycle takes approximately 3 weeks to complete, most infestations will be cleared within 3 weeks in a home (d) Once a home is infested it is not possible to clear the indoor infestation 98

Parasites of the Skin and Muscles 3 . Which of the following most accurately reflects the time it takes to rid a pet of fleas? (a) Flea products act as repellents so you should never expect to see fleas on a correctly treated pet (b) Most products kill fleas within 24 h provided they are used correctly and at the correct treatment interval; however, pets may constantly carry fleas if they are in an infested environment because no product acts as an effective repellant (c) It can take 90 days to kill fleas on the pet (d) There is no need to treat pets in the winter months as fleas are only a problem in spring and summer 4 . What is the primary source of cat fleas for reinfestation? (a) Pupae in the indoor environment (b) Pupae in the outdoor environment (c) Other pets – adult fleas usually jump from one pet to another (d) Pupae in the indoor and/or outdoor environment, as adult fleas rarely jump from one animal to another 5 . What is the best way to manage the environment in established cat flea infestations? (a) Treat all the pets and prevent them from entering the home (b) Treat all pets and use an insect growth regulator (IGR) as part of an integrated flea control approach, and vacuum/wash bedding (c) There is no need to treat the pet as long as the environment is treated with an IGR and insect adulticide (d) Turn down the heating in the home and reduce humidity to quickly clear the home infestation Lice 1. Which of the following statements relating to Trichodectes canis is most accurate? (a) This louse is able to infest a number of different animals as well as dogs (b) It is a biting/chewing (c) It is able to survive away from dogs for long periods of time (d) It is the only clinically significant louse of dogs 99

Parasites and Pets: A Veterinary Nursing Guide 2 . Which of the following insecticides is useful in treating Trichodectes canis infestations? (a) Moxidectin (b) Selamectin (c) Fipronil (d) All of the above 3. Which of the following statements is most true for the control of cat and dog lice infestation? (a) The environment must be treated to eliminate persistent life cycle stages (b) Treatment all year round is essential to prevent lice reinfestation (c) All in-contact pets of the same species should be treated when an infestation is identified (d) Owners may also become persistently infested with cat or dog lice 4 . What is the primary source of cat and dog lice for reinfestation? (a) Lice in the indoor environment (b) Lice in the outdoor environment (c) Contact with wildlife reservoir hosts (d) Close contact with other infested pets 5. Which of the following statements about dog lice is true? (a) Both sucking and biting lice species may be present (b) Only biting lice are clinically significant (c) Only sucking lice are clinically significant (d) Dog lice may also infest cats and people Mites 1 . Which of the following mites live in hair follicles? (a) Demodex spp. (b) Trombicula spp. (c) Otodectes cynotis (d) Sarcoptes scabiei 100

Parasites of the Skin and Muscles 2 . Which of the following is a burrowing mite? (a) Cheyletiella spp. (b) Trombicula spp. (c) Otodectes cynotis (d) Sarcoptes scabiei 3. What percentage of otitis externa cases in cats is due to ear mites? (a) 65% (b) 75% (c) 85% (d) 95% 4 . Which of the following mites have a free living stage? (a) Demodex spp. (b) Trombicula spp. (c) Otodectes cynotis (d) Sarcoptes scabiei 5. How long can sarcoptic mange mites live for off the host? (a) 1–2 days (b) 3–4 days (c) 5–7 days (d) 2–3 weeks Ticks 1 . Which is the most common tick infesting cats and dogs in the UK? (a) Dermacentor reticulatus (b) Dermacentor variablis (c) Ixodes hexagonus (d) Ixodes ricinus 101

Parasites and Pets: A Veterinary Nursing Guide 2 . Which of the following ticks transmits Ehrlichia chaffeensis? (a) Amblyomma americanum (b) Dermacentor reticulatus (c) Dermacentor variablis (d) Rhipicephalus sanguineus 3 . Which of the following is an effective treatment for Lyme disease? (a) Fenbendazole (b) Doxycylcine (c) Levamisole (d) Allopurinol (e) Albendazole 4. Which of the following organisms appear as piroplasms in stained blood films? (a) Babesia spp. (b) Borrelia spp. (c) Ehrlichia spp. (d) Hepatozoon spp. 5. Which of the following ticks transmits tick-borne encephalitis? (a) Dermacentor reticulatus (b) Dermacentor variablis (c) Ixodes hexagonus (d) Ixodes ricinus Leishmaniosis 1. What is the vector of Leishmania spp.? (a) Fleas (b) Mosquitoes (c) Sandflies (d) Ticks 102

Parasites of the Skin and Muscles 2 . Which of the following is a treatment for leishmaniosis? (a) Fenbendazole (b) Doxycycline (c) Milbemycin oxime (d) Miltefosine 3 . Which of the following treatments for leismaniosis is r­ estricted for human use only? (a) Fenbendazole (b) Amphotericin B (c) Milbemycin oxime (d) Miltefosine 4 . Which dog breed is resistant to Leishmania? (a) Ibizan hound (b) German shepherd dog (c) Cocker spaniel (d) Boxer 5. Which body organ is known to be impacted by treatment of ­leishmaniosis? (a) Heart (b) Liver (c) Kidney (d) Spleen 103